Esters of o-phthalic acid have been detected in the air, soil and water throughout North America. These pollutants probably enter the environment by elution from plastic materials. Phthalate esters have no short-term effect on human health but teratogenic and mutagenic effects have been recorded for lower organisms (rats, mice and some species of fish). Phthalate esters easily enter and concentrate in the tissues of aquatic organisms and consequently may be subject to concentration in food chains. The proposed research will measure levels of phthalate esters in water and sediment from marine regions. Rates of degradation of phthalate esters in the water column and in aerobic and anaerobic sediments will be determined and the effects of light, nutrients and temperature examined. The numbers of aerobic and anaerobic bacteria capable of hydrolyzing phthalate esters will be determined in water and sediment samples. Pure cultures of these bacteria will be employed to determine the most readily biodegradable phthalate ester(s) currently in use. Pure cultures of bacteria which grow aerobically on all three isomers of phthalic acid have been isolated and also crude enrighments growing anaerobically, in the presence of nitrate, on o-phthalic acid. Numbers of marine bacteria which degrade o-phthalic acid will be determined in water and sediment samples. Enrichment cultures will be established to isolate more physiological types of bacteria (nitrate-respiring, sulfate-respiring, photosynthetic and fermentative) which anaerobically degrade phthalic acids. The pathway of anaerobic catabolism of o-phthalic acid will be examined initially with pure cultures of denitrifying bacteria. Techniques involved will include the metabolism of possible intermediates by whole cells and cell-free extracts; trapping of radioactivity, from C14-labelled o-phthalic acid, by suspected intermediates; isolation of mutants which accumulate intermediates.